The gun bluing process is known throughout industry as black oxide. It is only in the gun business that its refered to as "bluing". Black oxide is a hot dip immersion process which causes the surface of the steel to turn a dark color. If you sandblast a part before processing it comes out flat black. If a part is polished before processing even though you run it thru the same tank you get the gun-blue finish typical of firearms. Du-Lite is a brand name of black oxide chemicals, but there are dozens of suppliers of these chemicals and you really can't tell the difference in the end result. So, if you want the shiny finish the problem is you have to polish the parts. Unless your gun is a real dog, no matter how careful you are doing the polishing you will be reducing the value of your gun. There is simply no way to polish off the parkerizing without it being obvious when the gun is blued. The prep for parkerizing is sandblasting, and while this is also changes forever the original factory finish, it does not alter the surface as much as polishing. My recommendation would be to black oxide the receiver and trigger frame, and replace all of the other parts with EXC condition parts which are still available in the parts sets. This will get you as close as you can get to original - many of the WW2 guns had flat black (i.e. sandblasted but not polished) receivers and trigger frames with all of the other parts polished. An EXC condition parts set will cost you approx $1000 but you can retrieve 1/2 of that by selling your parkerized parts. (maybe more). You can black oxide over or thru parkerizing so it will not be necessary to polish the receiver and trigger frame. The exception would be if your parkerizing is one of the later light grey processes which can result in a thick, coarse finish. WW2 parkerizing is iron-manganese phosphate which is dark and smooth and the thickness of the finish is only 0.0002"-0.0004". (yes - those are ten-thousanths). The debate of to-refinish-or-not-refinish has raged here before but your case is a little different since your gun has been parkerized. But please, please do not have someone polish the receiver and trigger frame unless they are already so damaged that it wont matter. My $0.02 Bob